function openInterests = constructOpenInterestMap()

%Get data from Oslo Stock Exchange web page
osxLink = 'http://oslobors.no/ob_eng/markedsaktivitet/derivateUndOverview?newt__ticker=OBX&newt__isin=NO0000000021';
data_string = urlread( osxLink );
data_string = data_string( strfind( data_string,'<!-- Main area content: START -->' ):...
    strfind( data_string,'<!-- Main area content: END -->' ) );

%Extract open interests
openInterests = containers.Map( );
tempInd = 1;
while true
    tick_ind = strfind(data_string(tempInd:end), 'OBX1' );
    if isempty( tick_ind );
        return;
    end
    tick_ind(2) = tick_ind(2)+tempInd;
    ticker = data_string( tick_ind(2)-1:tick_ind(2)+strfind(data_string(tick_ind(2):tick_ind(2)+10),'<')-2 );
    c11_ind = strfind(data_string(tick_ind(2):tick_ind(2)+400),'c11');
    start_ind = strfind(data_string(tick_ind(2)+c11_ind:tick_ind(2)+c11_ind+20),'>');
    stop_ind = strfind(data_string(tick_ind(2)+c11_ind:tick_ind(2)+c11_ind+20),'<');
    num_str = data_string(tick_ind(2)+c11_ind+start_ind(1):tick_ind(2)+c11_ind+stop_ind(1)-2);
    
    openInterests( ticker ) = str2double( strrep( num_str,',' ,'' ) );
    tempInd = tick_ind(2);
end

end